Low sloped edge ring for plasma processing chamber

ABSTRACT

Embodiments of a cover ring for use in a plasma processing chamber are provided. In one embodiment, a cover ring for use in a plasma processing chamber includes a ring-shaped body fabricated from a yttrium (Y) containing material. The body includes a bottom surface having an inner locating ring and an outer locating ring. The inner locating ring extends further from the body than the outer locating ring. The body includes an inner diameter wall having a main wall and a secondary wall separated by a substantially horizontal land. The body also includes a top surface having an outer sloped top surface meeting an inner sloped surface at an apex. The inner sloped surface defines an angle with a line perpendicular to a centerline of the body less than about 70 degrees.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application a continuation of co-pending U.S. patent applicationSer. No. 12/207,695, filed Sep. 10, 2008, which is herein incorporatedby reference.

BACKGROUND OF THE INVENTION

1. Field of Invention

Embodiments of the present invention generally relate to a cover ringfor use in a plasma processing chamber.

2. Description of the Related Art

Semiconductor processing involves a number of different chemical andphysical processes whereby minute integrated circuits are created on asubstrate. Layers of materials which make up the integrated circuit arecreated by numerous plasma processes, such as chemical vapor deposition,physical vapor deposition and the like. Some of the layers of materialare patterned using photoresist masks and etched using plasma etchingtechniques to form the structures and devices utilized to formintegrated circuits.

During plasma etching processing, the energized gas which drives theetching process may not be uniformly distributed above the substratebeing etched. The plasma non-uniformity may contribute to poorprocessing results, particularly near the edge of the substrate. Someetching chambers utilized chamber components such as edge and coverrings to improve processing results. However, as critical dimensionsshrink and fabricators strive to pack move devices on a singlesubstrate, processing techniques and components must be improved inorder to enable next generation products in a timely and cost effectivemanner.

Moreover, by-products may form on chamber components during the etchingprocess. These by-products require chamber components to be periodicallycleaned to prevent inconsistent or undesirable processing results.Improvements to chamber component designs which reduce potentialcontamination sources and the time between cleaning and/or componentreplacement is beneficial. Thus, there is a need for improved chambercomponents.

SUMMARY

Embodiments of a cover ring for use in a plasma processing chamber areprovided. In one embodiment, a cover ring for use in a plasma processingchamber includes a ring-shaped body fabricated from a yttrium (Y)containing material. The body includes a bottom surface having an innerlocating ring and an outer locating ring. The inner locating ringextends further from the body than the outer locating ring. The bodyincludes an inner diameter wall having a main wall and a secondary wallseparated by a substantially horizontal land. The body also includes atop surface having an outer sloped top surface meeting an inner slopedsurface at an apex. The inner sloped surface defines an angle with aline perpendicular to a centerline of the body less than about 70degrees.

In another embodiment, a cover ring for use in a plasma processingchamber includes a ring-shaped body fabricated from a yttrium (Y)containing material. The body includes a bottom surface having an innerlocating ring and an outer locating ring. The inner locating ringextends further from the body than the outer locating ring. The bodyalso includes a top surface having a substantially horizontal main topsurface, a substantially horizontal inner top surface and asubstantially horizontal land. The main top surface is positionedoutward of and above the inner top surface. The inner top surface ispositioned outward of and above the land.

In some embodiments, the cover ring is fabricated from bulk yttriumoxide (Y₂O₃).

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings.

FIG. 1 depicts a schematic diagram of one embodiment of an exemplaryplasma etch chamber that may benefit from embodiments of the invention;

FIG. 2 is a partial schematic cross-sectional view of the cover ring ofFIG. 1; and

FIG. 3 is a partial schematic cross-sectional view of another embodimentof a cover ring.

It is to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements and features of oneembodiment may be beneficially incorporated in other embodiments withoutfurther recitation.

DETAILED DESCRIPTION

Embodiments of the present invention provide chamber components withenhanced etching performance and service life. In one embodiment, thechamber component is a cover ring adapted to engage a substrate disposedon a substrate support pedestal.

FIG. 1 depicts a schematic, cross-sectional diagram of one embodiment ofan exemplary plasma processing chamber 100 that can benefit fromembodiments of the invention. The embodiment of the chamber shown hereinis provided for illustrative purposes and should not be used to limitthe scope of the invention. One example of a plasma processing chamberthat may be adapted to benefit from the invention is a DPS AdvantEdge™etch reactor, available from Applied Materials, Inc., of Santa Clara,Calif. It is contemplated that other plasma processing chambers may beadapted to benefit from the invention, including those from othermanufacturers.

The chamber 100 comprises a vacuum chamber body 110 having a conductivechamber wall 130 and bottom 108. The chamber wall 130 is connected to anelectrical ground 134. A lid 170 is disposed on the chamber wall 130 toenclose an interior volume 178 defined within the chamber body 110. Atleast one coil segment 112 is positioned exterior to the chamber wall130. The coil segment(s) 112 may be selectively energized by a DC powersource 154 that is capable of producing at least 5V to provide a controlknob for plasma processes formed within the processing chamber 100.

A liner 131 is disposed within the interior volume 178 to facilitatecleaning of the chamber 100. The byproducts and residue of the etchprocess may be readily removed from the liner 131 at selected intervals.

A substrate support pedestal 116 is disposed on the bottom 108 of theprocess chamber 100 below the gas diffuser 132. A process region 180 isdefined within the interior volume 178 between the substrate supportpedestal 116 and a diffuser 132. The substrate support pedestal 116 mayinclude an electrostatic chuck 126 for retaining a substrate 114 on asurface 140 of the pedestal 116 beneath the gas diffuser 132 duringprocessing. The electrostatic chuck 126 is controlled by a DC powersupply 120.

In one embodiment, a cover ring 102 is disposed around an outerperimeter of the pedestal 116 and substantially circumscribes thesubstrate 114. A portion of the cover ring 102 may be disposed under theedge of the substrate 114. In one embodiment, the cover ring 102 iscomprised of a yttrium (Y) containing material, for example, bulkyttrium oxide (Y₂O₃). The material of the cover ring 102 providesenhanced corrosion resistance, thereby improving the service lifetime ofthe chamber component, while reducing maintenance and manufacturingcost. Additional details about the cover ring 102 will be discussedbelow in connection with FIG. 2.

The support pedestal 116 may be coupled to an RF bias source 122 througha matching network 124. The bias source 122 is generally capable ofproducing an RF signal having a tunable frequency of 2 kHz to 13.56 MHzand a power of between 0 and 5000 Watts. Optionally, the bias source 122may be a DC or pulsed DC source.

The support pedestal 116 may also include inner and outer temperatureregulating zones 174, 176. Each zone 174, 176 may include at least onetemperature regulating device, such as a resistive heater or a conduitfor circulating coolant, so that the radial temperature gradient of thesubstrate disposed on the pedestal may be controlled.

The interior of the chamber 100 is a high vacuum vessel that is coupledto a vacuum pump 136 through an exhaust port 135 formed through thechamber wall 130 and/or chamber bottom 108. A throttle valve 127disposed in the exhaust port 135 is used in conjunction with the vacuumpump 136 to control the pressure inside the processing chamber 100. Theposition of the exhaust port 135 and other flow restrictions within theinterior volume 178 of the chamber body 110 greatly influence theconductance and gas flow distribution within the processing chamber 102.

The gas diffuser 132 provides a conduit through which at least oneprocess gas is introduced into the processing region 180. In oneembodiment, the gas diffuser 132 may provide process gases to the region180 in an asymmetrical manner that may be used to tune the conductanceand gas flow distribution described above that are caused by the otherchamber components (i.e., location of the exhaust port, geometry of thesubstrate support pedestal or other chamber component) so that the flowof gases and species are delivered to the substrate in a uniform, orselected, distribution.

In one embodiment illustratively depicted in FIG. 1, the gas diffuser132 includes at least two gas distributors 160, 162, a mounting plate128 and a gas distribution plate 164. The gas distributors 160, 162 arecoupled to one or more gas panels 138 through the lid 170 of theprocessing chamber 100, and are also coupled to at least one of themounting or gas distribution plates 128, 164. The flow of gas throughthe gas distributors 160, 162 may be independently controlled. Althoughthe gas distributors 160, 162 are shown coupled to a single gas panel138, it is contemplated that the gas distributors 160, 162 may becoupled to one or more shared and/or separate gas sources. Gasesprovided from the gas panel 138 are delivered into a region 172 definedbetween the plates 128, 164, then exit through a plurality of apertures168 formed through the gas distribution plate 164 into the processingregion 180.

The mounting plate 128 is coupled to the lid 170 opposite the supportpedestal 116. The mounting plate 128, which is fabricated from orcovered by an RF conductive material, is coupled to an RF source 118through an impedance transformer 119 (e.g., a quarter wavelengthmatching stub). The source 118 is generally capable of producing an RFsignal having a tunable frequency between about 60 MHz and about 162 MHzand a power between about 0 and 3000 Watts. The mounting plate 128and/or gas distribution plate 164 is powered by the RF source 118 tomaintain a plasma formed from the process gases in the process region180.

FIG. 2 is a partial sectional view of one embodiment of the cover ring102. The cover ring 102 has a body 202 comprised of a yttrium (Y)containing material. In one embodiment, the body 202 may be comprised ofbulk yttrium oxide (Y₂O₃) or other suitable material. Alternatively, thebody 202 may comprise yttrium (Y) metal, yttrium alloy and the like. Inyet other embodiments, the body 202 may be comprised of yttrium dopedmaterials, such as yttrium doped quartz, yttrium doped aluminum (Al)metal, yttrium doped aluminum oxide (Al₂O₃), yttrium doped aluminumalloy or yttrium doped aluminum nitrogen (AlN).

In the embodiment of FIG. 2, the body 202 includes an outer diameter 204and an inner diameter 206. In one embodiment, the inner diameter 206 ofthe cover ring 102 is about 11.50 to about 11.75 inches. The innerdiameter 206 of the cover ring 102 includes a main wall 208 and asecondary wall 210. The main wall 208 has a diameter less than adiameter of the secondary wall 210. The main and secondary walls 208,210 generally have a vertical orientation, with main wall 208 having agreater length in the vertical direction than the secondary wall 210.The main wall 208 is also below the secondary wall 210.

A step 212 is defined between the main wall 208 and the secondary wall210. The step 212 includes a substantially horizontal land 214 extendingbetween the main and secondary walls 208, 210. The step 212 defines asubstrate receiving pocket such that the perimeter of the substrate 114extends over a portion of the land 214, as shown in FIG. 1.

The body 202 of the cover ring 102 also includes an inner locating ring216 and an outer locating ring 224 extending from a bottom surface ofthe body 202. The inner locating ring 216 includes an inner wall 218, abottom 220 and an outer wall 222. The inner and outer walls 218, 222 aresubstantially vertical and concentric in orientation, while the bottom220 is substantially horizontal. The inner wall 216 has a diametergreater than the diameter of the secondary wall 210.

The outer locating ring 224 is disposed outward of the inner locatingring 216 and includes an inner wall 226, a bottom 228 and an outer wall230. The inner and outer walls 226, 230 are substantially vertical andconcentric in orientation, while the bottom 228 is substantiallyhorizontal. The bottom 228 of the outer locating ring 224 projects ashorter distance from the body 202 than bottom 220 of the inner locatingring 216. The outer wall 230 of the outer locating ring 224 lies on theouter diameter 204.

The inner and outer locating rings 216, 224 define a notch 242 in thebottom surface of the cover ring 102. The notch 242 is configured toengage a mating feature on the pedestal 116, such that the cover ring102 is precisely located on the pedestal 116 within the chamber 100.

The top surface of the body 202 includes an outer sloped top surface232, an inner sloped top surface 236 and an inner top surface 240. Theinner top surface 240 is substantially horizontal in orientation, andextends from the inner sloped top surface 236 to the secondary wall 210.

The outer sloped top surface 232 and the inner sloped top surface 236meet at an apex 234 of the cover ring 102. The inner sloped top surface236 generally slopes upward and outward, and is orientated at an angle238 of less than about 70 degrees relative to a line definedperpendicular to a centerline of the cover ring 102, for example, asdefined by the bottom 228 of the outer locating loop 224. In oneembodiment, the angle 238 is about 60 degrees. The slope of the innersloped top surface 236 has an orientation projected in the horizontalplane which allows ions and reactive species utilized during in-situring cleaning to have a more direct impact the projected surface. Thus,the ion impact energy and/or quantity of reactive species impinging onthe top surface 236 during in-situ cleaning of the ring dramaticallyimproves cleaning of the cover ring 102. The shape of the cover ring 102significantly increases the number of substrates processed prior torequiring the cover ring 102 removed for ex-situ cleaning outside thechamber 100. Compared to conventional rings, the improved cover ring 102has demonstrated an improvement of RF hours between clean from 300RF/hrs for convention rings to about 1000 RF/hrs. Moreover, since theslope of the inner sloped top surface 236 has an orientation thatenhances in-situ cleaning, less etch by-products, particularly polymerby-products commonly present during metal etch processes, such asaluminum etching, are present on the cover ring 102 after in-situcleaning. With less by-products on the cover ring 102, the potential forparticle defects during subsequent processing is advantageously reduced.The cleaner cover 102 ring also enhances substrate to substrate etchingresults, and as demonstrated by reduced microloading effects along withallowing structures to be precisely fabricated closer to the edge of thesubstrate (as compared to conventional techniques).

FIG. 3 depicts another embodiment of a cover ring 300 which may bebeneficially utilized in the processing chamber 100 described above,among other plasma processing chambers. The cover ring 300 generallyincludes a body 302 that may be fabricated from the materials identifiedabove with reference to the body 202 of the cover ring 102.

In the embodiment of FIG. 3, the body 302 includes an outer diameter 304and an inner diameter 306. In one embodiment, the inner diameter 306 ofthe cover ring 102 is about 11.50 to about 11.75 inches. The innerdiameter 306 of the cover ring 102 includes a main wall 308 and asecondary wall 310. The main wall 308 has a diameter less than adiameter of the secondary wall 310. The main and secondary walls 308,310 generally have a vertical and concentric orientation, with main wall308 having a greater length in the vertical direction than the secondarywall 310. The main wall 308 is also below the secondary wall 310.

A step 312 is defined between the main wall 308 and the secondary wall310. The step 312 includes a substantially horizontal land 314 extendingbetween the main and secondary walls 308, 310. The step 312 defines asubstrate receiving pocket such that the perimeter of the substrate 114extends over a portion of the land 314 when positioned on the pedestal116, similar to the land 214 of the cover ring 102 shown in FIG. 1.

The body 302 of the cover ring 102 also includes an inner locating ring316 and an outer locating ring 324 extending from a bottom surface ofthe body 302. In one embodiment, the inner locating ring 316 and theouter locating ring 324 may be essentially identical to the inner andouter locating rings 216, 224 of the cover ring 102 described above.

In one embodiment, the inner locating ring 316 includes an inner wall318, a bottom 320 and an outer wall 322. The inner and outer walls 318,322 are substantially vertical in orientation, while the bottom 320 issubstantially horizontal. The inner wall 316 has a diameter greater thanthe diameter of the secondary wall 310.

The outer locating ring 324 is disposed outward of the inner locatingring 316 and includes an inner wall 326, a bottom 328 and an outer wall330. The inner and outer walls 326, 330 are substantially vertical andconcentric in orientation, while the bottom 328 is substantiallyhorizontal. The bottom 328 of the outer locating ring 324 projects ashorter distance from the body 302 than bottom 320 of the inner locatingring 316. The outer wall 330 of the outer locating ring 324 lies on theouter diameter 304.

The inner and outer locating rings 316, 324 define a notch 342 in thebottom surface of the cover ring 102. The notch 342 is configured toengage a mating feature on the pedestal 116 such that the cover ring 300may be precisely positioned on the pedestal 116.

The top surface of the body 302 includes a main top surface 332, aninner top surface 334 and the land 314. The main top surface 332 and theinner top surface 334 are substantially horizontal in orientation, withthe main top surface 332 positioned outward of the inner top surface334. The inner top surface 334 is recessed below the main top surface332, while the land 314 is recessed below the inner top surface 334.

A wall 336 is disposed between the main top surface 332 and the innertop surface 334. The wall 336 has a substantially vertical orientation,and is concentric with the wall 310.

The substantially horizontal orientation of the top surfaces 332, 334promotes improved in-situ cleaning of the ring by allowing more direction impact and exposure to more reactive species. As discussed above,the improved cover ring 300 has demonstrated a significant improvementof RF hours between cleans, reduces particle generation and reducedmicroloading effects.

Thus, embodiments of a cover ring have been provided that allow devicesto be fabricated closer to the perimeter of the substrate thanconventional designs by promoting plasma uniformity and reducedmicroloading. Moreover, the configuration of the ring enhances cleaning,thereby improving substrate to substrate processing and reducing thepotential of particle generation due to incomplete particle removalduring cleaning.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A cover ring for use in a plasma processing chamber, comprising of: aring-shaped body fabricated from a yttrium (Y) containing material, thebody comprising of: a bottom surface having an inner locating ring andan outer locating ring, the inner locating ring extending further fromthe body than the outer locating ring, the inner locating ring having aninner wall, the inner wall facing a centerline of the ring-shaped body;an inner diameter wall having a main wall and a secondary wall separatedby the substantially horizontal land, the secondary wall having adiameter greater than the main wall less than the inner wall of theinner locating ring; and a top surface having a substantially horizontalmain top surface, a substantially horizontal inner top surface and asubstantially horizontal land, the main top surface positioned outwardof and above the inner top surface, the inner top surface positionedoutward of and above the land.
 2. The cover ring of claim 1, wherein thebody is fabricated from bulk yttrium oxide (Y₂O₃).
 3. The cover ring ofclaim 1, wherein the body is fabricated from a material selected from agroup consisting of yttrium metal, yttrium alloy, and yttrium dopedmaterials.
 4. The cover ring of claim 1, wherein the secondary wall andthe substantially horizontal land define a substrate-receiving pocket.5. The cover ring of claim 1, wherein the bottom of the outer locatingring extends below the bottom of body less than the bottom of the innerlocating ring
 6. The cover ring of claim 1, wherein the inner diameterwall has a diameter from about 11.50 inches to about 11.75 inches. 7.The cover ring of claim 1, wherein the inner locating ring and outerlocating ring define a notch in the bottom surface